1. Field of the Invention
The invention is directed generally to conveying and marking apparatus and methods, and more particularly to an apparatus that can load, convey, and mark discrete pieces at high speeds. In preferred embodiments, the invention permits marking on opposite sides of the pieces and marking the pieces with high resolution, multicolor and/or composite images in registration. In embodiments, the apparatus and methods may be used to provide for direct customization of printed edibles by consumers, over the Internet or in a retail setting, for example.
2. Description of the Related Art
A conventional apparatus for printing discrete pieces is described in U.S. Pat. No. 4,905,589, comprising carrier bars attached to a conveying chain. The carrier bars are positioned side by side to form an essentially continuous conveying surface which follows a transport path. Pockets are provided in the carrier bars to carry small pieces, which are loaded into the pockets at an inclined portion of the transport path and printed on a horizontal portion of the transport path.
The design of the carrier bar systems limits the overall speed at which the pieces can be conveyed. Speeds of 50 to 75 feet per minute (15 to 23 m/min) are typical for conventional carrier bar systems, with 100 feet per minute (30 m/min) being a practical maximum. Above this speed, pieces begin to rattle in the pockets and pop out during transport.
Filling the pockets at high speeds also poses a problem. At higher speeds the pocket is exposed to the piece for a shorter duration of time. The pieces may skip over the pockets, or travel on the carrier bar surface, limiting the percentage of the pockets that can be filled reliably at high speeds (“fill efficiency”).
Another drawback of conventional conveying and marking apparatus is the difficulty of printing on two sides of a piece. In order to print on two sides of a piece transported in the carrier bar pockets, the pieces have to be loaded onto a drum to turn them over, as described in U.S. Pat. No. 5,878,658. Alternatively, U.S. Pat. No. 5,423,252 discloses an apparatus for printing on two sides of a solid article, such as a tablet or capsule, by transferring the article from a first belt or chain conveyor to a second belt or chain conveyor. Other carrier bar configurations are available in which tablets are vertically oriented (i.e., sitting on their edge) within a cavity having two openings for printing on opposite sides of the tablets. However, these vertically oriented carrier bars suffer from the same maintenance issues and the same limitations as to operating speed and throughput as the horizontally arranged carrier bar systems. Because of the way they are constructed, the vertically oriented carrier bars are limited to printing on a single lane of pieces, which limits throughput, and portions of the printing surface are obscured by multiple portions of the carrier bar.
There is also a need in the art for conveying and marking apparatus that can be used to print multiple images on a piece by holding the piece in registration between print stations without relying on vacuum or trapping mechanisms to secure the piece. U.S. Pat. No. 7,182,018, owned by the assignee herein and incorporated by reference, teaches methods and apparatus for conveying articles in registration between two print stations to form a composite, registered image using a vacuum or trapping mechanism to prevent the piece from skewing or yawing between printing steps.
U.S. patent application Ser. No. 09/587,108, owned by the assignee herein and incorporated by reference, teaches a system and apparatus for high resolution printing on edibles which permits a consumer to submit an image using a computer to a second computer so that a customized edible product can be printed with the image. This may be practiced over the Internet for example, or in a retail setting. There is a particular need for rapid handling of pieces to be custom-printed according to a consumer's preferences on an as-you-wait basis in a retail setting. However, conventional systems for printing on discrete pieces are generally too large to be accommodated in a retail setting.
In view of the foregoing description of the prior art and problems to be solved, one object of the invention is to provide a conveying and marking apparatus that provides for higher transport speed of discrete pieces, especially edible pieces. The ability to transport pieces at high speeds may be significant in increasing throughput in a mass production setting or, for example, in a retail setting where custom-printed edible pieces are prepared for consumers on an as-you-wait basis.
Another object of the invention is to provide for dual-sided printing on a piece without requiring transfer of the piece to a separate conveyor, preferably allowing multiple lanes of pieces to be printed.
Still another object of the invention is to improve the design of the cavity holding the piece, on one hand allowing greater fill efficiency of the pieces in the cavities, and on the other hand allowing the pieces to be securely held in place during transport, for example, to prevent skewing and yawing between printing steps.
Still another object of the invention is to provide a conveying and marking apparatus that takes up less floor space and uses fewer complex elements of construction, which features may be particularly attractive in a retail setting.
There is a particular need for these advances in the field of printing on edible pieces, as there is an increasing demand in this field for consumer-initiated and consumer-designed edible products. These applications require quick and easy changeover to permit different articles to be printed with different customized images, as well as high throughput of edible pieces for rapid turnaround of orders. These and other objects of the invention are achieved according to the invention described and claimed herein.